Trajectory of use over time of an oral tablet and a rectal gel for HIV prevention among transgender women and men who have sex with men

Cheng-Shiun Leu, Rebecca Giguere, José A Bauermeister, Curtis Dolezal, William Brown 3rd, Ivan C Balán, Barbra A Richardson, Jeanna M Piper, Javier R Lama, Ross D Cranston, Alex Carballo-Diéguez, Cheng-Shiun Leu, Rebecca Giguere, José A Bauermeister, Curtis Dolezal, William Brown 3rd, Ivan C Balán, Barbra A Richardson, Jeanna M Piper, Javier R Lama, Ross D Cranston, Alex Carballo-Diéguez

Abstract

We examined product adherence among 187 men who have sex with men and transgender women enrolled in a phase II, crossover trial comparing safety and acceptability of an oral tablet and a rectal gel used daily for HIV prevention. Participants reported adherence via daily text messages during 8-week periods. Trajectory analysis identified weekly patterns. Polytomous logistic regression identified characteristics associated with higher probability of trajectory group membership. We identified 3 groups per product: high-adherers (72% daily oral, 70% daily gel); decreasing-adherers (20% daily oral, 22% daily gel); and low-adherers (8% daily oral, 9% daily gel). Daily oral high-adherers (compared with low-adherers) were more likely to self-identify as male (OR = 4.76, 95% CI:1.35-16.67), to have more sexual partners (OR = 1.67, 95% CI:1.04-2.63), and to find the tablet easy to swallow (OR = 2.22, 95% CI:1.08-4.76). Daily gel high-adherers (compared with low-adherers) were more likely to be older (OR = 1.16, 95% CI:1.05-1.28), to find gel application easier at the last few applications (OR = 2.27, 95% CI:1.01-5.00), and to report a change in routine if gel was not used (OR = 5.26, 95% CI:1.23-100.00). Characteristics of participants likely to be high-adherers to product use vary according to product. Evaluation of acceptability prior to phase II/III trials could identify participants likely to maintain high adherence.

Keywords: PrEP; SMS; adherence; microbicides; trajectory.